When the Lisbon Maru tied up near Stonecutter's Island off Kowloon in September 1942 she was 22 years old. With a history of taking Japanese migrants to the United States, she was no stranger to transportations.

On September 25th 1942, almost 1,850 POWs were shipped across to her from Shamshuipo POW camp. Over the next two days, several of the sickest men were removed, and when she sailed for Japan on the 27th some 780 Japanese soldiers had also been taken on board for repatriation.

All went well until some 120 miles south east of Shanghai, when, at 07:00 on October 1st, she was hit by a single torpedo fired by the American submarine Grouper. The Lisbon Maru shuddered to a halt.

During the day the Japanese troops were taken off onto a Japanese destroyer and another troopship, but the POWs were left battened down in the holds. They stayed there for 26 hours, then broke out as the boat began to settle. Japanese shipping in the area made no attempt to help; in fact they shot at men in the water. Losing hope of rescue, most of the prisoners started swimming towards nearby Islands, but eventually the Japanese started picking them up. By the end of the day, however, 825 men had died either on board the ship or in the waters round it.